The present invention relates to an inspectable tunnel which can house the different cable installations that run through cities generally located in the pavements, forming, in this way, networks to supply the inhabitants with power, lighting, data, TV and communications in general.
At present, the objectives of the engineers, both of city councils and liberal professionals, is none other than to minimize the negative impact made on cities when it is necessary to install a new type of utility.
Although in a summarized form, it is convenient to review the different utilities required by a modern city and their characteristics with the aim of focussing the problem we are attempting to resolve.
Usually, the utilities to be considered are:    1. Sewage network, wherein normally large-sectioned pipes located in the longitudinal axis of the street or roadway are used. They are installations which are consolidated in cities and difficult to position in a utility tunnel, both for technical reasons and the high execution cost of the possible utility tunnel.    2. Drinking water supply network. Here we have a case similar to the above, worsened by the high pressure worked with and the negative effect that this would have on the other installations located in the theoretical tunnel (flooding, short circuits, etc).    3. Town gas installations. The existing safety standards make it impossible, or at least costly, to share a space with other installations, e.g. electricity.    4. Electricity. It has a negative effect on other communications installations, creating interferences, electrical noises and other problems.    5. Lighting installations. They usually cause electromagnetic noise.    6. Cable TV. Its presence does not complicate other installations.    7. Pair telephony. Its presence does not complicate other installations.    8. Fibre optic communications, its presence does not complicate other installations.    9. Internet, safety, signalling, etc. Its presence does not complicate other installations.    Any utility to be installed inevitably has to go through the following stages:            Perform a study of the networks already installed.        Analyse the existing networks to see the useful space, defining the location of the new network.        Designing and rethinking the new network.        Digging up the pavement and excavating the trench.        Fitting the network pipes.        Covering the trench.        Replacing the pavement.        
Without a doubt, all or a large part of the phases described are resolved with an inspectable tunnel. Due the difficulty in execution and high cost, only in a very few occasions are the infrastructures in cities equipped with an inspectable tunnels that accommodate the different utility installations.
An inhabitant of any country is used to going out in the morning to the street to find that the pavements have been dug up, e.g. to install a new utility (currently in Spain, fibre optic for cable TV and communications) Probably the year after he/she will observe that his/her street has been again dug up to replace a power cable, etc.
There is no doubt that the world's cities have to be modernized, adapting their infrastructures to the progresses of science (telephony and communications) and to safety standards (burying the overhead electricity installations), etc. All of this is executed with one criterion, where the opportunity to invest and investor's choice of the time it will be done, predominates. This causes the constant opening of trenches, with differences in time ranging from a few months to several years. The results is none other than causing problems to the inhabitants, shopkeepers and a high fuel cost due to the traffic jams caused by this work.